The invention relates generally to electromagnetic drives.
Of particular interest to the invention are electromagnetic drives of the type having two vibratory masses which are coupled with one another via at least one leaf-type spring. One of the vibratory masses includes the armature of the drive whereas the other vibratory mass includes an electromagnet. Advantageously, the latter vibratory mass also includes a housing which surrounds the leaf-type spring. The individual leaves of the spring are separated from one another via suitable spacers and clamping devices are provided for rigidly pressing the individual leaves of the spring together. The vibratory mass which includes the armature is connected with the center of the leaf-type spring whereas the vibratory mass which includes the electromagnet is connected with the clamping devices via suitable connecting elements. The connecting elements and/or the vibratory mass which includes the electromagnet compensate for or absorb the predominant part or the entire change in spacing between the ends of the leaf-type spring which occurs due to the deflection of the spring.
In the known drives, the connecting elements are fixed against rotation and transmit the moments of force generated at the ends of the leaf-type spring to the vibratory mass connected with the ends of the spring. Since the connecting elements are also constructed so as to compensate for or absorb the changes in distance between the ends of the spring, they exhibit a certain amount of resilience with respect to the moments of force. This leads to the result that the moment patterns and force patterns in the individual plate-like springs of the group of springs changes. Concomitantly, the spring constant of the spring system are affected.